SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5ada627dd99d127e196f92cd23a7161d5ae3c37b6284ad0a299406bb55fbb67b' 
  AND token = '2UM16mIifJuvlvIcIcyMcputH7x5snPhIaejxHfLsRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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