SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b568d389c9884030c3ebda2fc00e799bdcc5ce45f838df86fbdb31debf0e83b8' 
  AND token = 'dUOxbCML3Nb7aJrM6UWcBoB7SCDJvXnppCorPFsQ0Oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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