SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f4fe06a6be5b4c0f94f5edda546f9a0eb5eba0af2889c68e0d87696376032c4' 
  AND token = 'N0ozDQV04jNlJcGeBjxccg4OREDPk/medkTP9wqo65Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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