SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86f51f968e943a94e4a028be17d3e9ac7a68fe381f5046b271f0a505c921c434' 
  AND token = 'NkU0meWygxFHSXctQQLtXOhWc2xacrFEIGr/LHXyqvU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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