SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '545fe281b73e207256afc7789d98625234426b25381acc1ac81ad440800d6e52' 
  AND token = 'vr6ckS4JqvHg4ZDwNwonsTo2Wl/cbo8zo8+PFcbV6sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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