SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '992e3f3e968d40036816eb84533671364fd31d64e369d5c0b655d9ecbcd2b48c' 
  AND token = 'AKzkOW9Kqpz0u9MFWzTsw/gBRKAKGIVhGQ9DsOwGDts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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