SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3cba779269c8300b52d713f754b970d5a561684586700dc09a246c800a0f14f' 
  AND token = '7nf1JJiQZnwzpXQp2ieZt7D0ofhE5KojqHg+AyRLXCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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