SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf08f10f1293fd1a516ac6b1c5cc576ff643f44170b4bab2a9d3560c091ed435' 
  AND token = 'rUJppY2yNQ1/VjWNLC3OI+UjBFqsFDflwxlSRuSBGDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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