SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '260251060d63753b6fedc86a7c54c2c88c9f6080409f80f9e00f8fa7992fac5b' 
  AND token = '9RkH8j222M+PqRC2dpjOP/eMiEfpFrsniP3kBvLzfxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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