SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c61995c7a1c9c1b6d32366dddf1542028afb4dbae69beefe2f7c171835d0655' 
  AND token = 'YVpy1pToWRfrWZKmhSUJ2Z5PQN8jCzUKkNBu1pkwZfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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