SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f434844d489bf5b1f2fad31baca61ec837490ba6fdb0b4262855ece0819235f3' 
  AND token = 'fUteMjxnLQeSq2sjVriO0gZ0voEEHm8DCp1G6OjcZ8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}