SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ffe87001b48e27bc82d4a12304986a774807c4633d2f05ad5cebe33219e9acc' 
  AND token = '8VV/h6EAwG7fwiKOz3HY59SFDM9jwdmVTQ5cMU+m6UM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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