SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa15536bf71dc4b9d88c08d1cc0cec20d7c66257af4d4072611b398786dc78b4' 
  AND token = 'PJlAHHawytaKbozcoA1CVtGtNJFKknyQolslU5qJ8W4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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