SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '045a453087500a7366229229b473a6342b825f6d0fc8a6bbfe0cbceb0e0b7e3c' 
  AND token = 'JHqGLN4gTptyBm/GuQzIaQQnwgFVYWIJtXgvCs2BRQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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