SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3db93017d664f6231b22158bb0def50e6b59e320829283b0f2279d58278bcd5' 
  AND token = '+QNXpQi8OvwiWuiwgPBpsWGy112krPkvbqU84qd/BFU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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