SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38588751138fe9c30867bb1997b4005351f228202540e12f0e1e3385abe0b8f8' 
  AND token = 'dufAzR1/du3Lvn7eq9NLmBiZsPBhtSNGn5v1DrBaL5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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