SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6e577d390110854f4fa42ab376c24293dbe97539747023f25bd212c804bc4ac3' 
  AND token = 'dPuME46czbQZLrlvGCR4PervfJOItVlRlKhPWtbUC0Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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