SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b6331f8a51966426b950a2c2a43e7da2c2f441500107bb82af136eefb983010' 
  AND token = 'cB+PphHjZxJTJttvYqCtg0ALWQWe6QdcM2uDYH9Wric=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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