SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96b7ddec7a1857b33d736646f625c010f8dc740dcb4bd9fe127086a8625d1421' 
  AND token = '0Zl76+MGktEV7bf3HpBU/YsyFzU+zmuNU4L7qbPrBjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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