SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50dd9f0fa3e5cab4a7b3766bb08a72f20d775ddcaeda6934317699860f9bde78' 
  AND token = 'PucM27mYDlIYmVIMpG7VytIYuZIsXcIVV63kdPlFzSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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