SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c20daa48b1c6e279083c36ae0bc4c142692139be2a8ec647e540bdce38b31fad' 
  AND token = 'gr1euGaQA2ADZnezgT52BmxndHZaUS4jfdyCGYRFtHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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