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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f34a3d5c4d4654fdbc5d3c3d551562b5f49fdc249d2fbf0eed382a969f427c8' 
  AND token = 'fjnD/0D0hGuwHA8OwUUVVWWkeN/iuvNNu+lqokYlwNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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