SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba3e8ff7a5de25a51660df637ccd37abd875463fb1add4497d262724ef50db93' 
  AND token = 'V2hjmMknVFGie9mF1Djjz+OcnOCwX+SCP9G+11zKrBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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