SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2bae8d1cf5405bc4dff489a2800adbe847b65bfa02ee6892dfba18f33a1fafb' 
  AND token = 'kThJWTXn3xiAjBjr2IDmM5TBct+ljgx9aynEZ8LFr0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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