SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6c6a465b1f8f772ee41e5af1772e06d8053a3464529b630e0e40a8fb798f42d' 
  AND token = 'SZCWs5Y4IBNUkC6qT/juWZMoPLvo2XSRKSBuzC7HySQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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