SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72e51567a9079fd9a51a786d294542cdd2c1cc67baa09a68568859df0a609a79' 
  AND token = 'tsuJ3mnsngVwFLD8ez7RfSOHpYCFNE5SuGko0M9iMcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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