SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88b6834a86f8fd319b67a97ba23b8d81d821acfcfee21751e8e3302d0687f3c8' 
  AND token = 'LtQdWm20aDPeKahPqdxxNZsZKPcVXF0n7VF3S8Q3+yQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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