SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21e25b4dc023b9bbe8f6e859816bc3f99e4dda42598ee3f74b96fc26d7866e18' 
  AND token = '0ipCF+ROMaJQnJsYdP8Y0/sQKLwW7TcwwCMsUDeAxDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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