SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87e122df0e0d5bad748416c068f4a61e74e8e2be729c0da8185acecf5d191047' 
  AND token = 'cpdUedFrJINn3lkwJuCOdiYbhhj+rS3yVms+hoGjQjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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