SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da6d1d1761a1f96a623e6c7db406c86943b457ba81087072dc3051c1533d9d55' 
  AND token = 'gfZVlkU0I/oTwXLsalQVwsNzHYqdMA/EfNbsH6JL4ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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