SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '948ccb8259519c67994de078e9883673a4060366123e5f100d3b9997b7c1590b' 
  AND token = 'eudC05IwvmlgNbp43n5kIiyntIAAy1/StDOXC9DoCZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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