SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54959036208576d54e8eb5f4dde967ae27190324a71c81408070a3d1ea391af9' 
  AND token = 'DVCigLehzTmNoNfsFM70/Qk75bUJAJfhNwPXvJ1Pv/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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