SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ce323949b3ffdc51de721e17a6d9043c07268c6c4de55194334b791c908844' 
  AND token = 'TLYxlirjLXfYc+HYvwQv+6zLICXLWP8Z9VeTt3tKuJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}