SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7538b4da59cbc0e366a8a3de56f80c98c45e2de05564829becd9ea3f041e997' 
  AND token = 'RaP6HkB6kuf+jJQFYTajGaW5CupBT+hoEDGlhAXqdXQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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