SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cfa4eba553804ea4eb795e96d55698652a079d6470b78413db7d849863dc78e' 
  AND token = 'xr6z/eYZ1PTqGuclqvjqStTYiPsY3bXJylGJbwsimFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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