SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a21617e430839b0575b2978d4a8c64207c8ba44200a97154ac9f3c280608006' 
  AND token = 'hEUgpE37MbhugjJB1F+wyxdP2qovrCYQQz0EO+XMp6I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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