SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49855674d246e4d27169718f2844a0898cda373d6920b0e9e2f3135f672c4574' 
  AND token = 'rOv/YvdvKlWdLZFuoVpaGjnKq2OlPayRDXzZyVEdT2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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