SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d14995297af444bf6014826a7014b4065bf49ae427938411588481f4b85f52d' 
  AND token = 'ckUj+BGwLp6NqATPLI/34YDKHfZvyP5SBRNDRdyLhKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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