SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a08003f29f7e143e71703a5f8c2c199d7527f19f9e383abaf36284eb4f9955f' 
  AND token = '/6I5A3vet3KIqU+ce4XVwsZCZUm4onJh9W1XPtsgzv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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