SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59cf1f5e6910d0ab8b04ca7eec2b53ac12c62c1eec5d2fe78bad16d443fb584f' 
  AND token = 'MRUEhLRJQ9fBqzCQRfpsE/5i4RFW3uhuZ8FOU3axWwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}