SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a549876a767ebcedabb07fbb8abd7ebde9d2cf75bd83303f2bdc879f937bcea1' 
  AND token = '+L3+dm87apmVNd44m6OhrA09z4hK6IUMhbUErD/LVGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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