SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ac9c1a37600b6caff31728591adc38e0eba52a505ad17434fd87b79c3aba224' 
  AND token = 'n+q52kFP8uNeMKWKVKlBBY7hGRY0agaTWFcoN+SFRUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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