SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968e8043de9c3e47a3f766004b2e9021c853e53e53b4da90df4d888ad3a2cff1' 
  AND token = '9QgWq7DZDQZCg6jbcQzshvrbP46c7aiOF2JLGMPjxSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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