SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9a4691768299dfbe26f315c572699749fc431bc19aa4a1648c49f31d18115f04' 
  AND token = 'VzRZDhReQNLeytO/j0BDvtl2jZ1YqHXtc7EPqOyZJAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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