SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6692a010af8868089b9c9b65a87de9df45cdf8836f3963220729eea14d7966' 
  AND token = 'aQcbuUVwnVy6xMIVph4T5mV4TlU93CyPtJ6iEBIgi4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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