SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2dbf8cdeba43d0e3bd33c95d1ee4ae1e7f0926838cdb647ff5344600fabaca4' 
  AND token = '4qHNGtrICzt+uIzl0ih+P8kNdRPN8WJryhr9UAdkZYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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