SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50ef1a78639fc30c24b65029ae719a9faa60b21118a38f60c293b25e5db4d169' 
  AND token = 'Jx/BfqkBhPl4p2OvpdtzjWLUV2guiHqA2GxzA+s4ETA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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