SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00a39842392087d7bd9027f880216ebff29c8d2464075d27b212cdb62db3f68f' 
  AND token = 'BItezaBfUBcP4w2iCPSIjXEsPWhJfNgyvqmPGrC1x+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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