SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d0800308617b00078ea330fa3146b6f5c5fd85e2b0d6fdc36b75f8e64f14f99' 
  AND token = 'uRETeWVcRdmVe+hmidiZIZtylbPKHXulJRkO1kJMiag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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