SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '512329d2d20c4229760235f31376b53f90f79b590d5ca20c69cfb49d249b043a' 
  AND token = 'nFcpZ6dTrp7zqoSEfvraJDKtcAcKY3EaSqhYVetZqfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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