SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e394b765342206a7c6ab6a59fe35881aeba1464224e412191d666a180658a893' 
  AND token = 'xOLkR5ODFR44P/64rqRdF3dlhccNZqQNzdGys6SiQ/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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