SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'd278e24dfa18ffdd583d17bff4204247e0387ad369da12b7a9e15556c6655385' 
  AND token = '9+oYOXr4HendpPj8UR9p8wn0yDKcNkpymisluhy8YbI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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