SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4ed0abba9344d6116792c117c36747c3a752b7c5eb3b017dddc4a816fb77eda' 
  AND token = '6HpREr+eoGoqu+lyQ9sv/9BuqxjoNPxrihp6y4lNR18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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