SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bec435107e50c141371346cb85210e4b6e43d2674d302ada1f29538e54e238fc' 
  AND token = 'szmYNA5jQvgR+qh1xUSK87s+ux/gmQiDImiqOEVXUQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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