SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89f3660c0ad5f9df8a64e5efbe766c04374916ab1e6c0d541d0a9ec80fbc5743' 
  AND token = 'rTfXx89E3yo+b34nx/6CYxIyeAFLs20vkQP7BxH1IFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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