SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12ceb003bf3db2e6188eeaa904c1af5947a75a50d18150dfbe6d6153b508c2e5' 
  AND token = 'VDkxhgeGbFVTvCLL2rPV9YofkeZgbreB4MbeB+fClFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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