SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f51c639fda4f597d43a8190bcb7ed35c8d59408fcb9563c407c98c279432727b' 
  AND token = '5OKCh+jAcVFOZ1OellDosoV9KZG4vdi65R5L0KBuHLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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