SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f40e1f162bc81585e90f646f677bbde53446bc754668ab3f95a750bfd8e3fc7' 
  AND token = 'RBg0KtnfLDoAS+tuDL2NIhef6X7AMnKQ0bngQ+1/mJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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