SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e71fcef76865da04ef434b9a835f925972aea20a01e9b0848d839e867e950423' 
  AND token = 'pSOgBe6nxWvsjQ0TESnHepWAgEV0zT5JwvNpsalFtTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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