SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '053a099d6fa0f947bccce9f006b4914133317ed6f5b228e24b37aa2e312587ad' 
  AND token = 'SCv+fpuAQfZGGvQQ0gSfc3ttDGvXz0nmzydThAVlVYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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