SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4f31374bfde30a2fb515c81ebb953f96cbbc780a12b493d1d80535cb832ff9a' 
  AND token = 'DMSQrotyxjQTWseB3EER0yw+MunHzZrqydwZU6PzbUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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