SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52d28c8f628fea52052b47eeef516108223fb896ca5dc0b669c454581594ab52' 
  AND token = 'zJRW+E59ksRrztSYX1IfeiPc6i/hv582bbgGSz9BHRk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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