SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f258744b951319d879d464023475953b09acf7f6796129c36ea96c9085689a4' 
  AND token = '1fNy6RwDvhtEtHhmIi6MH7jMPQRaUrjxXCRNoPoX2tw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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