SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31645a84a45efb1f754729038259570264d8e799b5676de5fb295b2e906ed5ce' 
  AND token = 'VhjB7Crm7kbOvl9TKg+zdHqJCMzAmKFmX9ud33FCJXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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