SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82978d08a3b703a781eaa72910ae90cf15706770b66e1520752ce543759fd35a' 
  AND token = 'E/lFtuQXE0/DTVwNAsa0N40m37kDUPTf+OYk3cO6Vb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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