SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4936d09977fa23d28b46f74445798031f71cf2c5b6686d0be2df6c2b58ea8d' 
  AND token = '6BN8VaK+vStg4fa6RWoQnJg3NWqVSMZDNqZmzGLhuBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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