SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5851599d66849c9f1aec5e93c5b60f804e519dc068258755206a80e672f7854' 
  AND token = 'Vwqh/RakvZ0Tl46akVlQ0vmWzW8fn9F+GDEHGefiBiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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