SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1936b572617accf2cc35980e816fd30b135c9475019e406c6d20668a2696fcfe' 
  AND token = 'Ro/OIdTb4dhmREEfo1MrfmL3N/GGtL4EsOobjrz3MC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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