SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42f21b5835a0e1986b0bcb8d5818918c7bfc2b6e690f69707b7b5b3eecc81cc5' 
  AND token = 'OmaqaJH+oN3tolGcVTcyr19sUm7cOQ7SEAWy6QuOMjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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