SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9438b50245aa27462f62de7972e08eb98cf8bbd8a39c11a368676df8aa370bcd' 
  AND token = 'qMR2zkfnFlTaPX7+1R7nyvaGzGlMvzSFg2wfPJOBciI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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