SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40c14aed4ce09d7d168237218541e79e82f1c06d951d0c511bdf6baaaa2598df' 
  AND token = '0JT5mEpl0VZ7eFnbsUm9Yw3jPieXnSlMs5UN7JIZTdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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