SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b98ad45baa086d1ffd7fa0ae67a912e9d5986a126ea6f5cb33fc82672d3dbe2' 
  AND token = 'qtBUpvsXlzqJgTaJ4u8sVd3jI7mHaKMc0h7H8URqVQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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