SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a1e1feb3c070687458362dff5784bfa2e9d895579bc65a64bdde8d2640ac816' 
  AND token = 'uM1MhHSWsYPKUq1qRZTcXtGxBZKlAaTeEvQoQmm1jGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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