SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ed294e50667f83c7e6e0349822de7be56fab1b003030017427adec1733c688f5' 
  AND token = 'S0HJXQ5eSKfXYhrSIKlYTLYB0IRxkFhEgiFOdIZinRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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