SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2ec40b96a4adeeed013d3b078c3635c9efaab944844e9637d4d9b1ae3ed4430' 
  AND token = 'LtroGlgl+EgEAmm74WapQegVTFrannd53IZFThpPuKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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