SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb7a8798e844d75dda0350fba7c53f88a5c992c2951b6921730fd05796364f1d' 
  AND token = 'xpEk/Xys6gMKr6EvMdomUwh3tusGCN0UEJeB2+st3LY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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