SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '374148b82047bd5b0f42cc3931bb1e8bfd4173360bff183463c28fee77a52b64' 
  AND token = 'dKP6x0qn4OuG9XXZ1fwm+tJMlQuC8R09C/97qSjLdPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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