SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0621e51a5c4f78d464662f19e14acf86eaefda066594c7dfa76800e90d38b185' 
  AND token = 'n4cCzsBiach3I+bJHkMaVEGbFB5PBjtjNSopAzt/iYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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