SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '363ec88804ba3746480402038c2fa751abb807795ef4d171adf0813410a01722' 
  AND token = '4Ds3dMnErROQh6efo6LSw+TyvLsxjhaVRnqmzOvEwAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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