SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f27d68cfd191df57bc030a629ae84f483286b61f67aa5342f95b8903e7324bf' 
  AND token = 'jvkxDG/f4r5nyum+Jhtj4DwQPD9eUVyLtVy/21oufRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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