SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b48993805f2919f5bfbe53144d24e08721402008a3bccc7f63e4905fb1f8ed0' 
  AND token = 'NbyIn7nQco/ToiSM1ehK/KqSpeqUFnHP6EE4eBQvTSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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