SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '649d4e95a43132e97db2e063be2a5733e4313a0f998a353da00b26c519f336e7' 
  AND token = '0i8Rwlvhx/8FrvRJs14BzLBUj1zKgADnj28yiqFBR3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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