SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad6984be51cffd1771369d453abbc6b7242e8b95b3607072bdb2c332d8c21da9' 
  AND token = 'mAgxpGYc9Xqkb9ojscMHX8nBeYfmfZeHlwhiBV0echE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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