SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b29ccf7e177814e53f642dfa98bd29553bb5392ce7634627177fbabd077f9535' 
  AND token = 'djHv8S+kBGCRuke6qstVoP/a3ltLucbI/1ceOEKO17s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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