SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e82bb92d064067484bf146a86689dd09606b26418bc31a4544aa6f0e3816cb' 
  AND token = 'j+lcdIehb5hxRIatcTfMbC18SPcDyJatS9L3chNXXyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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