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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518abf3f7c1a9766041139d249cc0c03e2f2fd8fcbfc8b9fb1e3289628219363' 
  AND token = '+wqdLtq3WnHp7Rc0h6dg6kfe5/XUkqMdLiv/KYSM58E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}