SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55ea52334a4e62084ceace120bb6506a31bf0aff869404d37b0d589dfad95113' 
  AND token = '7QAx5exk9TnV+C1TOD2yhr3lwYmZUOOCvQprktG99tI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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