SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c4e6368a7ff9de233f32dee6667da94466ab218e617501ba245d54316717dfd' 
  AND token = 'OJtjJ1OPaGzoCq/IszMTEoKeiXsud71wcA2UzOTHAhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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