SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9c1787592c23c02eb6be3a271a990cfa48e4d21952eb51f55fda019d8cd32af' 
  AND token = '3/VLj9K31eI/iPq0pPT6imQkF8p4SGJFiZh8SsJFHhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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