SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfa86249546aa98b8a54d41e29ed42543f5e8789b6f340fa920970174f156cce' 
  AND token = 'DlxfnGEhSXPOwTaI6XPgb2K7F9UGiNZphgKAuzysoAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}