SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5075ac5a2c1956befc2ce1862262e60f55c8a8b337f38608fde2e847f00fdac0' 
  AND token = 'KuB5nTFBSC2mtVrukmykdYdlr9QaDgGfNdgXyKgK5Xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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