SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a2348fa8be8a93793861f56e02f7d298d4d3395460e579953bf39130b0a00b5' 
  AND token = 'FlbHGwqBxHVmjo/PTMMbTnHKYJ9Tg8Kw386QAxn+E2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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