SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5be9e0af798031122058208f2a59eb094a4e43034c8ff8d1ac1fb51e9b17dad9' 
  AND token = 'MXaanQk1cbVt8p3cv6gAIHcjw/BztVxWJcTB4lPSzAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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