SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd520014f1d6b9a8cea7bfd671bdec99eea70ca2870572ab2269320c668c58d2a' 
  AND token = 'U92v4hreQzpjKLQHKlBNTFiroJ8cWIE65cpe2fex0oM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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