SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f189723c9cae48b02718fdd315eb393fdbb11351814b3fd075c4bdd092e055c' 
  AND token = 'gyRg9fF1s3yTOHXBLVfWOm9COwAiU1gAV+wcBDghYeY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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