SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c168a6ecbae5bb09548689ea4a3156022bb0284da7ecd86d233dbc3aad0b5b' 
  AND token = '6M3RFV9B6CBpKr5Gk0jmrKFFhI/wnTo5h/e87CKdvJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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