SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8a733589391e8f080ef11a0a865b3f267f96ef9afd8003bf88a8df327f7bc91' 
  AND token = 'NzKepyh0jflU7IM96J8YqgUAciA4keBX6OvNljCk3vc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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