SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e55390feaf857b798ef7aafac1892b4e8cf6d32b5bb8eaf31b399727d46909c' 
  AND token = 'mpB4MpHXDhhmk7lEqGpTnFzqXPkpTHvObt5ZwIIyVRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}