SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f531d3cc3a447d61b36cff02c85a753b569de020dcfeb5da9e3639ee83f70293' 
  AND token = 'nzX43wNUwvjRTp62gAFk2eRq5XgbsTYEAPrG60xBF0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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