SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1af8e13dd8c0179a6082a5213409c10a164f71135f13d82b529ef738dedcd55' 
  AND token = 'pVJhjDjiBjS2HgRQNA/ZfZUhOoeW/TgtFfQ0zvkD+3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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