SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4670e8eddf3dc720669f892bf0fbacd071664f5d50903bf7795affed65bfa281' 
  AND token = 'XzMMAp/WtB0iUwD9M37MXlqBxZ+SKzovDu/I0MS7Qi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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