SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7187086a4f40ef8d5344eb783c8ef2cd1f58fe0cefcd6456530d255128260f50' 
  AND token = 'gJ2rl09aMqD/jShdfpWuqpJ8OmvxBMrzdk+rmkNdLRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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